


Soul For a Soul

by Jastra



Category: Undertale (Video Game)
Genre: Angst, Child Death, Death, Desperation, Drama, Emotional, Emotional Manipulation, Feels, Frisk watches, Gen, Gender-Neutral Frisk, Gender-neutral Reader, Hurt/Comfort, Murder, Protective Sans, Reader Is Frisk, Sans kills a kid
Language: English
Status: Completed
Published: 2015-11-29
Updated: 2015-11-29
Packaged: 2018-05-04 00:17:55
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 3,626
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/5312513
Author URL: https://archiveofourown.org/users/Jastra/pseuds/Jastra
Summary: <blockquote class="userstuff">
              <p>After showing mercy to Asgore, peace returns to the underground world and you end up living together with Papyrus and Sans. However, after a year passes and things remain the same, unrest starts to lift its head among the monsters and Sans knows that even the king or queen can't keep you safe forever.</p><p>The key to everyone's freedom finally arrives in a form of another human child. But, even though humans are supposed to their friends now, Sans knows that this cannot continue.<br/>6 children were dead already. One more death was not going to matter. Sans knows that he has to take a life to set everyone free, even if you'd hate him for the rest of his life.</p><p>A single soul isn't worth anything.</p>
            </blockquote>





	Soul For a Soul

**Author's Note:**

  * For [SwordandthePen](https://archiveofourown.org/users/SwordandthePen/gifts).



> Hey hey, this is for the wonderful and supportive SwordandthePen who requested something like this. Well I was already working on it, but the request made me really interested in the idea of Sans murdering some innocent kid.  
> I might write an epilogue/ second chapter of the monsters leaving the underground and Frisk refuses to follow Sans who has to carry the kiddo with him or something. You are pretty disappointed with him.  
> Inspired by this pic by nyublackneko  
> http://nyublackneko.tumblr.com/post/133260330582/a-comic-expanding-from-my-all-hail-king-papyrus

Sans sat on the porch of the house that belonged to the two skeleton brothers. Well, to be honest it now belonged to you as well, after all, the two had invited you to stay with them now that you were a true inhabitant of the underground world.

The shorter skeleton watched you play as the evening slowly settled over the snowy village that showed no signs of quieting down. The passage of time had always been a troublesome issue for the people trapped in there, but thankfully the the glow of the gems changed intensity and hue as the time passed, giving the snowy area now a lovely orange hue. The color and light reminded you of a setting sun.

Sans exhaled heavily as he kept his watchful eye on you while you played with the monster kid you had met in the waterfall. The two of you were building a snowman that slightly resembled Papyrus.

' _The resemblance is uncanny...'_  Sans snickered slightly in his mind and wondered where his brother had disappeared to. Most likely he was out there in the woods, training or re-calibrating his puzzles. It was truly astonishing how Papyrus still wanted to join the royal guard after everything that had happened.

Sans sighed again and pulled the fur-lined hood of his jacket up, the wind was unusually biting today.

 _'Sometimes I really envy you, Papyrus. How do you manage to keep that excitement and enthusiasm for life so easily.'_  The undead wondered as he flexed and yawned loudly, wondering if he should just call it a night. But he refused let you stay out alone, not after he had started to hear the unhappy and unsatisfied rumors and murmurs among the monsters.

When you or Papyrus weren't around, Sans had caught some of the monsters talking about how they'd be free after getting just one more soul.

A year had passed since your decision to stay trapped and not to kill Asgore in order to get out alive. Things had been relatively peaceful, what else could they be when everyone was trapped either way?

But...your presence in the underground had not gone unnoticed and while the Snowdin village had remained calm and quiet, in the darker parts of the core and waterfalls, monsters were murmuring and getting restless. A sense of apathy had washed over the majority of the monsters.

Having a chance of getting out of the underground world at their grasps had given them hope and joy, and they had all amassed to the capitol only to hear that the human was now their friend and under the king's protection. It had really smashed everyone's dreams down, but then again, people had accepted it since they all agreed that you were an innocent soul and didn't deserve to die.

But, that didn't mean the anger and disappointment would not exist. It was quite tempting really. They had gathered 6 souls over the centuries and with one more, they'd be free. What was one single soul, from one measly human when there were billions of them up there. It really didn't sound like a lot to ask, but everyone who knew you, would not even think of hurting you. But eventually, someone would have to die in order for them all to get out. Who knows, maybe you'd die of old age before that happened. Perhaps it would be easiest to just attack the next person who fell. Then, it wouldn't be personal.

Sans, along with many others didn't find the queen's decision to consider humans as friends pragmatic. If they took every human as a friend who fell into their world, they would never get out. Would they wait till they died of old age or suffer some lethal accident? To Sans it felt even worse than just outright killing someone quickly and painlessly as possible.

 _'Frisk..I will protect you, no matter what.'_  The short skeleton thought as you helped the armless monster kid push yet another snow ball on top of another.  _'So kind and innocent. I'm not going to let anyone hurt you. You've earned your place in our world."_  Sans thought and looked pained, staring at the white snow covered ground bitterly  _'But eventually we have to kill someone, I just hope no one is going turn on you...and if they do, I'll kill them all.'_

Sans' mood had darkened, not noticing you turn to look at him with confused look on your face.

"What is one life worth?" The short, black eyed skeleton muttered. ' _We love you, Frisk. Your worth to us comes from the mercy you've shown us and the connections you've made with us...a stranger would be worthless, just a face in the crowds."_

Sans lifted his head all alarmed when he saw from a corner of his eye someone tall approach you. His eye flashes blue for a moment, ready to pierce or throw the attacker away from you, but the light quickly fades away when he realizes that it is just the greater dog.

You giggle and laugh at the great armored dog who jumps around, panting. It pats your head playfully and you pat it in return, making the white furred dog leave all satisfied and happy.

 _'False alarm.'_  Sans thought tiredly, trying to relax. You weren't in danger, not really with Asgore and the queen protecting you and most of the monsters would come to your aid if you ever got in trouble.

Just one more soul and they'd be all free. As much as Sans hated to admit it, he had been thinking and pondering that idea many times. A single death and they'd all could go back to the world above Mount Ebbot. Humans couldn't be their friends until that day. What were they supposed to do? Stay in the underground world till the world ended? What was one soul worth in a grander picture? 6 children were dead already, what was one more to that? After that was done, no monster or humans had to suffer because of something that happened centuries ago.

They all had been trapped in this small, lightless world so long, it was maddening and broke everyone's spirits. Their freedom was so close, and the key was already there, but they just couldn't do it.

You notice Sans looking as if he was lost in his thoughts and hurry over to him, taking the shorter skeleton's hand.

"Sans, come help me make the snowman look like Pap...I can't get the face right." You say all excited, making Sans snap out of his thoughts. He looks baffled and alarmed for a few seconds, but quickly grins at you and puts his right arm around you to pull you against him as you two walk back to the monster kid who looks all excited.

"Sure thing kiddo, maybe afterwards we can grab something from Grillby's."

You lead Sans over to the monster kid and the snowman that to him it looks just half tipped over snowman with an expression that looked like Papyrus when he was all angry at his pun jokes.

"Heh, we will have to get it a cape as well." The shorter brother says and laughs a bit when you hug him happily.

* * *

However, the happy moment you share with the Sans and the kid gets interrupted when some of the villagers hurry over to you, some looking scared and confused, others angry. Some rushed to the tall dog guard to tell what was on their mind, but they were too far for you to hear what they were saying.

"Sans?" You ask curiously and though you had been sure the skeleton had been some distance away, he was now standing directly behind you with hand protectively on your shoulder. You two watch he villagers start to murmur between themselves, clearly worried and in shock.

"What's happening?" You wonder a bit fearfully since they eye you every now and then, pointing...but before the skeleton can answer you, you see Papyrus running towards you two, exhausted and in shock.

You can see right away that something is not right. Some monsters from the entrance run to the ones near you and they start to crowd up. Something big had happened. Some of them eyed you all worried while others looked at Papyrus and Sans. In general there was a feeling of disbelief, worry and sorrow in the crowds.

It feels very strange, but, you are almost sure that there was also some other emotion in their eyes...hope?

Some monsters looked devastated and horrified when they heard what ever the news were. Shaking their heads and whispering "no". You try and listen what they are saying but can't make out much through the chatter. However, you are pretty sure you hear the word "Murder."

"Sans, listen there is a h.." Papyrus starts all exhausted, trying to catch his breath, but stops when she sees you. His black eyes go wide and he quickly pulls Sans with him, not wanting you to hear what he has to say.

 _'What is going on..'_  You wonder, quickly realizing that you are standing there alone with the snowman as the villagers gather into groups and Papyrus keeps whispering something to Sans all worried and clearly shocked. The brothers were doing their best not to let you hear anything.

You start to feel isolated among the people and fear starts to creep into your hear. _'Is this about me?'_  You wonder and keep your eyes on Sans who listens calmly to what Papyrus has to say, only for him to get a shocked look on his face that is shadowed slightly by the hood.

"Papyrus, I will do it...get Frisk.." you hear the shorter skeleton say and the taller brother quickly turns to you. But, you have no intentions of not knowing what is going on and hurry over to the two, despite Sans giving you a stern and somewhat angry stare.

"What is going? Is someone hurt?" you ask all worried. But Sans ignores you as Papyrus grabs your arm to pull you aside and back towards the house.

"Come here, Frisk, its probably just some boring adult stuff... We can draw something." the skeleton says gently and calmly, but from his tone you can hear that something is wrong.

You try and resist Papyrus as he guides you away, but when you see the look of disbelief on Sans' face and hear him whisper a word " Doggo? Dead?" You realize that something is really wrong. Had someone killed that dog that couldn't see anything that didn't move? He was so nice, always having time for you despite now knowing him that well.

You see Sans clenching his fists in anger and he starts to head towards the village entrance with some of the monsters following him. They had clearly been waiting for the older brother to act. You look at the blue clothed skeleton head towards the wooden bridge and he is clearly tense, but filled with determination. Something was horribly wrong and you knew it. And what ever it was, you wanted to know.

"Papyrus let go of me!" You cry out angrily, not wanting to be pulled away by the taller skeleton who quickly loses his grip on your arm when you pull away and dash towards the direction the group had headed to, not wanting to be left in the dark. You dodge and make your way through the dense group making it impossible for Papyrus to catch you again despite trying.

"Frisk...Human I order you to come back." You hear Papyrus' worried voice yell from behind the crown but his voice eventually gets lost into the loud chatter.

You figure out that since the villagers seemed to flee/gather from there, someone was approaching the village, someone who had possibly killed the dog soldier.

You see Sans ahead of you and with your small feet you quickly run past him towards the entrance and the wooden bridge that led into the Snowdin. The short skeleton notices you run was him and tries to catch you by the back of your shirt but you dodge his attempt like a cat.

"Frisk! Get back here!" Sans yells in worry and hurries after you, the group following you two a short distance behind.

You finally reach the entrance and what you see makes you shocked and fills your mind with a rush of emotions that varied from shock to joy.

There, near the wooden bridge and the sign in stood another human child, almost same age as you, perhaps a bit younger since you had grown up over the year. She was looking around with her dark and somehow lifeless eyes, clearly stressed and fearing for her life.

 _'Where did she come from? Did she fall down the same way I did?'_  You had thousands of questions in your mind and you wanted to ask them all. You were so happy too, knowing that you had another human to keep you company... Monsters were nice and you loved them, but humans were still different.

But, in your joyous feelings, you don't notice the monsters starting to approach the child who i was holding what looked like a small hammer in her hands. The crowd murmurs suspiciously and they share fearful and angry looks.

 _'What is going on? She is the same as me.'_  You think as you look around, not understanding any of this. The girl was on the verge of panic as she saw the different monsters approach her, but her dark eyes got hopeful shine to them when she saw you. She starts to approach you, clearly seeking protection from another human.

However, the stranger halts with a loud scream of terror when Sans dashed in front of you, his hood on, summoning a single bone that was aimed at the kid to keep her away.

You watch in shock as the kid shrieks in terror and dodges backwards, stumbling quickly and desperately up from the snow covered ground.

"Don't come any closer..." the skeleton says quietly and dangerously, his eyes pitch black.

The girl backs away a bit, holding the hammer in her hand defensively, but you can see that her hand is shaking.

"Sans? what is going on? She is just a human like me and.." You start but then you see it..there was dust on the girl's clothes and in her hair. Monsters turned into dust when they died. She couldn't have possibly..

Sans gives you a quick glance but ignores you, addressing the child that had come into the village.

"You killed the sentry in the woods, didn't you?" Sans asks quietly, standing between you and the strange kid who looks at the short skeleton with fearful look in her eyes.

 _'She..killed a monster? But she is clearly so afraid.'_  You think, knowing what she had done was unforgivable..but surely the monsters weren't going to kill a child. Then you realized it, the kid didn't have your power, she lacked determination that had allowed you to fix the mistakes you had made. She didn't have that luxury.

You remembered how scared you had been...wanting to defend yourself against those who attacked you, but you had been resilient, refusing to act violently. Not everyone was like you, some fought with instinct and had an iron will t live. You had the power of restart and load. You could fix a mistake if they happened...she couldn't.

Sans looked pained, clearly not wishing to do it...but it was all clear now. Either it was this child or you, and he'd choose to protect you no matter what. This kid had already killed someone and while the king and queen might forgive her and understand a fearful child...the others wouldn't. If he didn't take her soul, there was no guarantee that you'd be safe.

One more soul and everyone would be free. This had to be it...Soul for a soul. That sounded fair.

"Sans..No.." You whisper when you realize what was going to happen. The murmur in the crowd started to get louder.

_**"The last human soul, we'll be free...Not Frisk's...soul for a soul...this is not innocent."** _

They were going to kill the girl.

No

Sans was going to kill her.

 _'This is not fair, if I didn't have determination I'd be the one standing there about to get killed. You can't kill her just for acting out of fear.'_  You think desperately, knowing that it would be no different whether you or that kid stood there.

The monsters in the town were treating you almost as if you were one of them, not wanting to hurt you.

"Sans you can't! How is this any different from killing me?" You yell angrily and walk up to the shorter brother, grabbing his jacket and trying to pull him away, but it was useless. You hit him into back angrily with your fist. You just couldn't allow this to happen. There had to be another way.

"You can't do this. you just can't! I won't allow it. She's the same as me. I could just as well be standing there."

Words escape your lips before you even consider them and the monsters around you look startled and worried, considering your words.

Sans' eyes return to normal and he turns to you with a sad and sorrowful expression. The short skeleton pulls you into a tight hug, caressing your head gently, clearly not wanting this to happen.

Maybe things were going to be ok after all.

"What is one soul worth in the grander scale. One more soul, Frisk, that's all that it takes for you, me, Papyrus and all of us to be free. That child killed one of our friends..its only fitting that we take her soul in return." Sans finally says, his voice void of any emotion as he pulls back from the hug, looking you directly into eyes before getting up and turning back towards the kid who was paralyzed by fear.

You knew it, you knew right away from Sans' voice that he couldn't be persuaded not to do this, but that didn't mean you wouldn't try stopping him.

You look at the other child with horrified expression and she starts to back away slowly, mouthing the word "no.." over and over again, but the crowd was already blocking her way out of the village. You saw the monster kid push the girl back towards you and Sans when she backed away too close to the monster crowd. The tired girl fell onto her knees as the murmuring got louder and louder each passing moment.

"Sans...no no no..don't do this, I rather stay trapped in here forever. I'd be happy to, just please, don't kill anyone" You beg, trying to to prevent Sans from approaching the child who was trying to get up. You cling to his back and jacket, trying to get him to stop, but he keeps walking towards the child.

Sans sighs, gesturing something to Papyrus who quickly comes to you two.

"I know Frisk..but our people have suffered enough. I don't like doing this any more than you do, but...in the end one more soul is not worth anything."

With that, Sans pushes you to Papyrus and starts approaching the child again.

"Sans no! Stop it, don't do this. No one has to die." You cry out as Papyrus does his best to keep you away from the scene, pulling you towards the house.

"...I'm so sorry. Frisk." The tall and innocent skeleton says...and knowing him he probably didn't wish it either, but in the end even he wanted to see the over world and if it meant that they'd have to take a soul of someone who had killed one of them..so be it.

"Papyrus make him stop...I..I'm the same as her. I've made the same mistakes." You try despite knowing that Papyrus had no idea what you were talking about while Sans did to some level. The tall skeleton kneels down in front of you, his back facing the crowd.

"Don't watch.." Papyrus whispers and embraced you. Over his shoulder, you can see Sans closing in on the kid, with his other eye glowing with blue light. You hide your face against Papyrus' shoulder.

The short skeleton watched the fearful young girl who was holding her hammer up as a way to defend herself. It was completely understandable that she had defended her from a monster...but still...he had to do this.

The crowd kept the wall so that she couldn't escape, but none of them watched, some even made mournful gestures at the fearful child. Someone pulled the monster kid too into the crowd, shielding his eyes.

_'Its either her or Frisk...she doesn't mean anything to us. She is a stranger, worth nothing.'_

"No hard feelings kiddo.." Sans finally sighs and with a one swift and deadly move, he pierced the kid's body with a bone spike, tearing her soul away.

You start weeping against Papyrus' shoulder when you hear the last scream of pain and terror the child lets out before dying. "Its over now.." papyrus comforts you as you look over his shoulder to see a beautiful purple glow from among the crowd and in the middle of them all, stands Sans with purple soul in his hands.

Next to him lies a body of a child, the snow around her turning red.

You bury your face against Papyrus' shoulder.

You'd never look at Sans the same way again.


End file.
